Presently, the industrialized countries have adopted national solar energy utilization programs. One of the trends in the utilization of solar energy is the construction of solar photoelectric modules incorporating solar energy concentrators.
Known in the art is a solar module with a composite parabolic solar energy concentrator and a solar receiver disposed in an outlet section and cooled by means of a liquid (cf. U.S. Pat. No. 4,045,246. The module is constructed as follows: The concentrator having a reflecting surface is contrived as a discrete assembly, the outlet cross section whereof contains a sealed chamber, with a photoreceiver disposed on the bottom thereof. The liquid circulating inside the sealed chamber operates as a heat-transfer medium. An inlet section of the concentrator is covered with a transparent material.
The liquid coolant in the space in front of the solar receiver results in high losses of light passing through the layer of liquid and in the reduction of the photoreceiver efficiency.
The joints between the concentrator and the sealed chamber wherein the receiver is disposed and the liquid is circulating and between the concentrator and the transparent material in the inlet section neither provide for reliable sealing of the concentrator reflecting surface nor prevent environmental effects. The result is that the properties of the concentrator reflecting surface are impaired and the concentrator's efficiency is decreased.
There is known a solar energy collector whose basic component is a composite parabolic concentrator with an aperture angle .alpha. (cf. U.S. Pat. No. 3,899,672).
This prior-art collector is designed as follows: A spherical surface member mounts a plurality of discrete composite parabolic solar energy concentrators. The spherical member accommodates conduits filled with heat-transfer medium. The concentrators are disposed on the surface of the spherical member in such a way as to locate the heat-transfer medium conduit in the outlet section.
The foregoing construction does not permit protecting the concentrator reflecting surface against dust, moisture and air, with the result that the optical efficiency of the concentrators and the service lives thereof are substantially reduced.
There is also known a solar photoelectric module (cf. U.S. Pat. No. 4,166,917) comprising a composite parabolic solar energy concentrator with an aperture angle .alpha., designed in the form of a sealed transparent bulb filled with gas and provided with a reflecting coating on the side walls which are bent on a predetermined radius to a cylindrical part of the bulb near the concentrator radiation outlet surface. The photoreceiver of the module is located near the concentrator radiation outlet surface and is equipped with a cooling system.
A metal bus disposed on a face side of the photoreceiver in the module operates as a heat and current conductor; the taper part of the bus constitutes a part of the design reflecting surface. A U-shaped metal bus disposed on the back side of the photoreceiver also serves as a current and heat conductor. Both buses are connected to electrodes which are sealed into the glass of the cylindrical part of the concentrator. In turn, the electrodes are connected to the external part of the cooling system.
The cooling system arranged outside of the sealed bulb is exposed to corrosion due to environmental effects. As a result the service life of the module is shortened.
Since heat emitted by the photoreceiver is sunk through the electrodes, the thermal energy is unevenly distributed in the receiver because heat is removed only at several points. Consequently, the efficiency and service life of the photoreceiver is decreased.
The use of several heat and electrical junctions, the location of the cooling system outside of the concentrator, and the need for accurate mating of the glass and metal taper surfaces bring about complications in construction and assembly of the module.
Considering the use of current- and heat-conducting electrodes made of high-alloy materials with quite a large cross-sectional area, the demand in said materials (including tungsten, molybdenum and cobalt) is high.